Possible Duplicate:
How to convert a number to string and vice versa in C++
in csharp
string s1="12345"
string s2="54321"
public double (string s1,string s2)
{
convert.todouble(s1) +convert.to-double(s2)
}
how i do in c++ because there is no conversion classs
In addition to the other answers, the easiest way (in C++11 at least) would be:
double add(const std::string &s1, const std::string &s2)
{
return std::stod(s1) + std::stod(s2);
}
If your compiler supports C++11, there is a function stod that converts a string to a double.
Your function will be just
return std::stod(s1) + std::stod(s2);
Use boost::lexical_cast for example.
double func (const std::string& s1, const std::string& s2)
{
return boost::lexical_cast<double>(s1) + boost::lexical_cast<double>(s2);
}
or use std::stringstream, strtod etc.
double doubleFromString(const std::string &str)
{
std::istringstream is(str);
double res;
is >> res;
return res;
}
c++11 contains std::stod which converts a string to a double. Otherwise you can use stringstreams or boost::lexical_cast<double>. Therefore your options are:
return std::stod(s1) + std::stod(s2); //(c++11 only), or:
return boost::lexical_cast<double>(s1) + boost::lexical_cast<double>(s2); //or:
std::stringstream ss1(s1);
std::stringstream ss2(s2);
double a, b;
ss1>> a;
ss2>>b;
return a+b;
Of course you could also go the c route and use sprintf.
I would go with using string streams, as you don't need support to c++11.
This article in cplusplus.com answers your question: http://www.cplusplus.com/reference/iostream/istringstream/istringstream/
But this is what I would do:
#include <string>
#include <sstream>
double function (std::string s1, std::string s2)
{
std::istringstream iss (std::string(s1 + " " + s2), std::istringstream::in);
double a, b;
iss >> a;
iss >> b;
return a + b;
}
